/*
 * Copyright (c) 2011 UPB
 * Copyright (c) 2017 NITK Surathkal
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Radu Lupu <rlupu@elcom.pub.ro>
 *         Ankit Deepak <adadeepak8@gmail.com>
 *         Deepti Rajagopal <deeptir96@gmail.com>
 *
 */

#ifndef DHCP_HEADER_H
#define DHCP_HEADER_H

#include "ns3/address.h"
#include "ns3/buffer.h"
#include "ns3/header.h"
#include "ns3/ipv4-address.h"

namespace ns3
{

/**
 * @ingroup internet-apps
 * @defgroup dhcp DHCPv4 Client and Server
 */

/**
 * @ingroup dhcp
 *
 * @class DhcpHeader
 * @brief BOOTP header with DHCP messages.  This supports the following options:
 *        Subnet Mask (1), Address Request (50), Refresh Lease Time (51),
 *        DHCP Message Type (53), DHCP Server ID (54), Renew Time (58),
 *        Rebind Time (59) and End (255) of BOOTP
 *
 * @verbatim
   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     op (1)    |   htype (1)   |   hlen (1)    |   hops (1)    |
   +---------------+---------------+---------------+---------------+
   |                            xid (4)                            |
   +-------------------------------+-------------------------------+
   |           secs (2)            |           flags (2)           |
   +-------------------------------+-------------------------------+
   |                          ciaddr  (4)                          |
   +---------------------------------------------------------------+
   |                          yiaddr  (4)                          |
   +---------------------------------------------------------------+
   |                          siaddr  (4)                          |
   +---------------------------------------------------------------+
   |                          giaddr  (4)                          |
   +---------------------------------------------------------------+
   |                                                               |
   |                          chaddr  (16)                         |
   |                                                               |
   |                                                               |
   +---------------------------------------------------------------+
   |                                                               |
   |                          sname   (64)                         |
   +---------------------------------------------------------------+
   |                                                               |
   |                          file    (128)                        |
   +---------------------------------------------------------------+
   |                                                               |
   |                          options (variable)                   |
   +---------------------------------------------------------------+
   \endverbatim
 */
class DhcpHeader : public Header
{
  public:
    /**
     * @brief Get the type ID.
     * @return the object TypeId
     */
    static TypeId GetTypeId();

    /**
     * @brief Constructor
     */
    DhcpHeader();

    /**
     * @brief Destructor
     */
    ~DhcpHeader() override;

    /// BOOTP options
    enum Options
    {
        OP_MASK = 1,     //!< BOOTP Option 1: Address Mask
        OP_ROUTE = 3,    //!< BOOTP Option 3: Router Option
        OP_ADDREQ = 50,  //!< BOOTP Option 50: Requested Address
        OP_LEASE = 51,   //!< BOOTP Option 51: Address Lease Time
        OP_MSGTYPE = 53, //!< BOOTP Option 53: DHCP Message Type
        OP_SERVID = 54,  //!< BOOTP Option 54: Server Identifier
        OP_RENEW = 58,   //!< BOOTP Option 58: Address Renewal Time
        OP_REBIND = 59,  //!< BOOTP Option 59: Address Rebind Time
        OP_END = 255     //!< BOOTP Option 255: END
    };

    /// DHCP messages
    enum Messages
    {
        DHCPDISCOVER = 0, //!< Code for DHCP Discover
        DHCPOFFER = 1,    //!< Code for DHCP Offer
        DHCPREQ = 2,      //!< Code for DHCP Request
        DHCPACK = 4,      //!< Code for DHCP ACK
        DHCPNACK = 5      //!< Code for DHCP NACK
    };

    /**
     * @brief Set the type of BOOTP and DHCP messages
     * @param type The type of message
     */
    void SetType(uint8_t type);

    /**
     * @brief Return the type of DHCP message
     * @return The type of message
     */
    uint8_t GetType() const;

    /**
     * @brief Set the hardware information
     * @param htype Hardware type
     * @param hlen Hardware length
     */
    void SetHWType(uint8_t htype, uint8_t hlen);

    /**
     * @brief Set the transaction ID
     * @param tran The transaction number
     */
    void SetTran(uint32_t tran);

    /**
     * @brief Get the transaction id
     * @return The transaction id
     */
    uint32_t GetTran() const;

    /**
     * @brief Set the time when message is sent
     */
    void SetTime();

    /**
     * @brief Set the Address of the device.
     *
     * Only the relevant bits are considered (i.e., not the type and length)
     *
     * @param addr Address of the device
     */
    void SetChaddr(Address addr);

    /**
     * @brief Set the Address of the device
     * @param addr Address of the device
     * @param len Address length
     */
    void SetChaddr(uint8_t* addr, uint8_t len);

    /**
     * @brief Get the Address of the client.
     *
     * Note: the address is always 16-bytes long.
     *
     * @return Address of the client
     */
    Address GetChaddr();

    /**
     * @brief Set the IPv4Address of the client
     * @param addr The client Ipv4Address
     */
    void SetYiaddr(Ipv4Address addr);

    /**
     * @brief Get the IPv4Address of the client
     * @return IPv4Address of the client
     */
    Ipv4Address GetYiaddr() const;

    /**
     * @brief Set the DHCP server information
     * @param addr IPv4Address of the server
     */
    void SetDhcps(Ipv4Address addr);

    /**
     * @brief Get the information about the DHCP server
     * @return IPv4Address of DHCP server
     */
    Ipv4Address GetDhcps() const;

    /**
     * @brief Set the Ipv4Address requested by the client
     * @param addr Ipv4Address requested by the client
     */
    void SetReq(Ipv4Address addr);

    /**
     * @brief Get the IPv4Address requested by the client
     * @return IPv4Address requested by the client
     */
    Ipv4Address GetReq() const;

    /**
     * @brief Set the mask of the IPv4Address
     * @param addr 32 bit mask
     */
    void SetMask(uint32_t addr);

    /**
     * @brief Return the mask of the network
     * @return 32 bit mask
     */
    uint32_t GetMask() const;

    /**
     * @brief Set the Ipv4Address of gateway to be used
     * @param addr The Ipv4Address of the gateway
     */
    void SetRouter(Ipv4Address addr);

    /**
     * @brief Return the Ipv4Address of gateway to be used
     * @return The Ipv4Address of the gateway
     */
    Ipv4Address GetRouter() const;

    /**
     * @brief Set the lease time of the IPv4Address
     * @param time 32 bit time
     */
    void SetLease(uint32_t time);

    /**
     * @brief Return the lease time of the IPv4Address
     * @return 32 bit time
     */
    uint32_t GetLease() const;

    /**
     * @brief Set the Renewal time of the IPv4Address
     * @param time 32 bit time
     */
    void SetRenew(uint32_t time);

    /**
     * @brief Return the Renewal time of the address
     * @return 32 bit time
     */
    uint32_t GetRenew() const;

    /**
     * @brief Set the Rebind time of the IPv4Address
     * @param time 32 bit time
     */
    void SetRebind(uint32_t time);

    /**
     * @brief Return the Rebind time of the address
     * @return 32 bit time
     */
    uint32_t GetRebind() const;

    /**
     * @brief Reset the BOOTP options
     */
    void ResetOpt();

  private:
    TypeId GetInstanceTypeId() const override;
    void Print(std::ostream& os) const override;
    uint32_t GetSerializedSize() const override;
    void Serialize(Buffer::Iterator start) const override;
    uint32_t Deserialize(Buffer::Iterator start) override;

    uint8_t m_op;              //!< The DHCP Message type
    uint8_t m_bootp;           //!< The BOOTP Message type
    uint8_t m_hType;           //!< The hardware type
    uint8_t m_hLen;            //!< The hardware length
    uint8_t m_hops;            //!< The number of hops covered by the message
    uint32_t m_xid;            //!< The transaction number
    uint32_t m_mask;           //!< The mask of the network
    uint32_t m_len;            //!< The length of the header
    uint16_t m_secs;           //!< Seconds elapsed
    uint16_t m_flags;          //!< BOOTP flags
    uint8_t m_chaddr[16];      //!< The address identifier
    Ipv4Address m_yiAddr;      //!< Your (client) IP address
    Ipv4Address m_ciAddr;      //!< The IP address of the client
    Ipv4Address m_siAddr;      //!< Next Server IP address
    Ipv4Address m_giAddr;      //!< Relay Agent IP address
    Ipv4Address m_dhcps;       //!< DHCP server IP address
    Ipv4Address m_req;         //!< Requested Address
    Ipv4Address m_route;       //!< Router Option Address
    uint8_t m_sname[64];       //!< Server name (Padded for now)
    uint8_t m_file[128];       //!< File name (Padded for now)
    uint8_t m_magic_cookie[4]; //!< DHCP Magic Cookie
    uint32_t m_lease;          //!< The lease time of the address
    uint32_t m_renew;          //!< The renewal time for the client
    uint32_t m_rebind;         //!< The rebinding time for the client
    bool m_opt[255];           //!< BOOTP option list
};

} // namespace ns3

#endif /* DHCP_HEADER_H */
